1. The Field of the Invention
The invention relates to systems for retractably positioning a cover over an opening of a space and, more particularly, the invention relates to a lock for rope reels of an automatic swimming pool cover system that has ropes attached to the cover which extend through tracks to the reels that are driven to wind the rope onto the reels and in turn to pull the cover over the swimming pool.
2. State of the Art
The use of automatic or motorized swimming pool covers on swimming pools is well known. Examples of such are described in U.S. Pat. No. 5,913,613 to Ragsdale et al. (“the '613 patent) and U.S. Pat. No. 5,920,922 to Ragsdale et al. (“the '922 patent”).
Motorized or automatic pool cover systems of the type described in the '613 patent include some form of container at one of the pool to contain a retracted cover and to contain associated drive components. The container may be a recess or a well formed along a selected edge or a raised housing sometimes called a bench positioned at one end of the pool. Mounted in the well or housing is an elongated drum connected to a rotatable shaft which in turn is connected to an electric drive motor. One end of a flexible pool cover is secured to the drum. The drum is driven or rotated one way to collect the cover and open up the space (e.g., a swimming pool). The pool cover is extended over the top of the swimming pool by attaching draw cords or ropes to the opposite sides of the pool cover. The draw cords or ropes extend through groves formed in track that is fixed along two opposite sides of the space. One edge of the cover also slides in a groove of the track. The draw cords extend in the tracks down opposite sides of the pool and around a pulley rotatably fixed to the outermost end of their respective tracks. See U.S. Pat. No. 4,466,144 to Lamb and U.S. Pat. No. 3,979,782 to Lamb. Typically, the draw cord or rope is returned and secured to a collecting reel or rope reel which is rotatably carried on the same elongated shaft that attaches to and drives the cover-collecting drum.
Some systems have one rope reel for a rope at each side of the cover. One collecting reel may be carried on one side of the drum and the other may be carried on the other side. See U.S. Pat. No. 3,050,743 to Lamb and U.S. Pat. No. 4,060,860 to Lamb. It is presently preferable, however, to position both rope reels next to each other with pulleys positioned to direct the draw cords or rope to the appropriate reel. See U.S. Pat. No. 4,858,253 to Lamb. A coupling and double-dog clutch drivingly and alternately engage to drive the reels (to position the cover over the space) and to engage the drum (to wind the cover onto the drum and remove the cover from over the space) through the shaft. The double-dog clutch operates as illustrated and described in U.S. Pat. No. 5,105,481 to Lamb, the disclosure of which is hereby incorporated by reference.
The related art systems, although effective for the purposes designed, on occasion damage the pool cover fabric during the time it is being retracted on the collecting drum. Tearing or ripping of the cover fabric can occur when one side of the cover fabric is collected on the drum at a rate faster than the other side. Eventually, the cover fabric is damaged. Systems to avoid this problem and to avoid costly repairs of the pool cover fabric are not known.